Use an agent role when you already know which step you need. Use junior mode when you want the implementation workflow coordinated for you.
Match the role to the task
| Task | Role | Useful result |
|---|---|---|
| Understand the change before editing | Scope aligner | Done Criteria, affected code, risks, and a plan |
| Implement an agreed behavior test-first | TDD implementer | Changes, Red/Green evidence, and remaining issues |
| Explain and fix a failure | Scientific debugger | Diagnosis, reproduction, fix, and verification |
| Assess an existing change | Code reviewer | Verdict and actionable findings |
| Prepare messages or create local commits | Git committer | Message drafts or confirmed commits with evidence |
For explanations of existing code or architecture choices, use senior mode and its analysis skills.
Give a bounded assignment
Provide the relevant behavior or question, the files or diff to inspect, constraints, and the result you expect. State whether the role should make changes.
Use agent-code-reviewer on the current diff.
The requirement is that an empty tag selection returns every item.
Check the callers and tests affected by that behavior.
Return findings without modifying files.
Scope alignment and code review are read-only roles. Implementation, debugging, and committing can change the repository within the assignment and host permissions.
Read a role's result in context
Roles use different fields because they answer different questions. IDENTIFIED is a diagnosis; APPROVE is a review verdict; CREATED reports a commit result. Look at supporting evidence and limitations before deciding the next action.
Junior mode's handoff rules explain how these results contribute to a complete code-change task. A directly invoked role can finish its assignment while the wider project still has work to do.
Delegate when it helps
A separate subagent is optional. It needs host support and authorization, plus enough context to do the assigned work independently. Give it a clear boundary and avoid overlapping edits.
The owner remains responsible for checking evidence, resolving conflicts, and integrating the result. See Host integration for what the host controls.